Selective operating mechanism for air preheater by-passing dampers



1 Oct. 26, 1954 Q J w n-Kus 2,692,761

SELECTIVE OPER NG MECHANISM FOR AIR PREHEATER -PASSING DAMPERS FiledNov. 14, 1952 4 Sheets-Sheet 1 F I From forced To induced g- Draft FanDraft Fun Air 1 Q 1 20 22 23 i f INVENTOR Joseph Wuitkus Oct. 26, 1954 wus 2,692,761

J. SELECTIVE OPERATING MECHANISM FOR AIR PREHEATER BY-PASSING DAMPERSFiled Nov. 14, 1952 4 Sheets-Sheet 2 Fig. 5.

NEY

Fig. 4.

' Oct. 26, 1954 J. WAITKUS 2,692,761 SELECTIVE OPERATING MECHAN FOR AIRPREHEATER BY-PASSING D ERS Filed Nov. 14, 1952 4 Sheets-Sheet 3 INVENTORJoseph Woitkus Oct. 26, 1954 J. WAITKUS SELECTIVE OPERATING MECHANISMFOR AIR PREHEATER BY-PASSING DAMPERS Filed Nov. 14, 1952 4 Sheets-Sheet4 Fig. IO.

ATT6BNEY Patented Oct. 26, 1954 SELECTIVE OPERATING DIEGHANISM FOR AIRPREHEATER -Bit-PASSING DAMPERS Joseph Waitkus, Wellsville, N. Y.,assignor to The Air Preheater Corporation, New York, N. Y.

Application November 14, 1952, Serial No. 320,536

(01. ESL-6) 7 Claims.

The present invention relates to regenerative heat exchange apparatus ofthe rotary type and particularly to an improvement in dampers thatcontrol the lay-passing of one or both of the fluids that flow throughthe apparatus.

A regenerative heat exchanger of the rotary type comprises a rotor thatcarries heat transfer material, such as metal plates, that are firstcontacted by hot gases to absorb heat and are then moved to position inan air stream to impart the heat thereto. In the operation of such heatexchange apparatus it is sometimes necessary to by-pass part of thestream of air around the heat exchange material in the rotor, forexample to avoid cooling the plates to a temperature that might inducecorrosion of the plates or clogging of the spaces therebetween. In othersituations it may be desirable to by-pass part of the stream of gases.Heretofore, by-pass dampers have been provided in the duct workassociated with the gas or air sides of the preheater. Such by-passesinvolve the provision of additional by-pass duets with dampers thereinin addition to the normal inlet and outlet ducts for the gas and air;which adds to the cost of the preheater.

The present invention contemplates the provision of by-pass dampers foreither the gas or air passages of a rotary preheater with theseby-passes built into the structure of the heater itself. The inventionfurther provides for the selective and automatic operation of thedampers in the built-in by-passes so as to enable the by-passing ofvarious amounts of gas or air.

The invention will be best understood upon consideration of thefollowing detailed description of an illustrative embodiment thereofwhen read in conjunction with the accompanying drawings in which:

Figure 1 is a sectional elevational view of a regenerative air preheaterof the rotary type embodying built-in by-passes in accordance withthe'present invention.

Figure 2 is a transverse sectional view as seen on the line 2-2 inFigure 4 showing the parts of the damper operating mechanism on therotor and enclosing housing.

Figure 3 is a fragmentary view on an enlarged scale showing a portion ofthe preheater and illustrating the built-in by-pass dampers andoperating means therefor.

Figure 4 is an elevational view as seen on line 4- 3 in Figure 3 andillustrates a single damper actuator in association with one of theoperating stations. Figure 4a is a similar view illus- 2 trating thesame damper in partially opened position.

Figure 5 is a vertical sectional elevation on line 55 of Figure 4showing the component parts of the damper operating mechanism inoperating relationship.

Figure 6 is a perspective vieW showing the damper operating mechanism atone station.

Figures 7 to 9 are schematic views showing the rotor in relation to anend plate and illustrating various fluid flow conditions; in Figure '7all dampers are closed and there is no by-passing of either gas or air;in Figure 8 with all dampers opened there occurs a maximum lay-passingof air and gas, respectively; and in Figure 9 some of both the gas orair are by-passed, but not a maximum of either.

Figures 10a to 10 are developed or schematic views of the damperoperating mechanism illustrating the several stages of operation as adamper opens and closes.

In Figure l the numeral Ill designates a cylindrical rotor comprising acircular shell l2 connected by radially extending partitions M (Figures2 and 3) to a rotor post It: which is driven' by a motor it throughreduction gearing. The rotor It is enclosedwithin a housing Hi providedwith end plates 24], 2| that are formed with circumferentially spacedapertures 22, 23 for the passage of streams of hot gas and the air to beheated to and through the rotor. Conventionally the rotor It] carriesheat absorbing material in the wedge-shaped compartments formed betweenthe radially extending partitions M; such material, for example, beingin theiorm of metallic plates 24 spaced to form vertical passagesthrough the rotor. In addition to the radial partitions l4 the rotor hascircumierentially alined transverse partitions or diaphragms 28 whichfurther subdivide the Wedge-shaped compartments into a series ofchambers. Imperferate portions 21, 23 (Figures 7 to 9) between the gasand air openings 22, 23 in the endv plates 24), 2| are engaged by radialseals (not shown) on the partitions Hi to preclude cross-flow of air tothe gas passage while circumferential seals 29 (Figures 1 and 5) on theedges of rotor shell l2 engage parts ofthe end plates 28, 2| to preventby-passing of the rotor in through the annular space 3 1 between it andthe housing 58.

In accordance with the present invention, the rotor I0 is filled withthe heat transfer plates 24 except for the chambers 30 that form anannular band adjacent the shell l2 at the perimeter of the rotor. Thechambers 30 in this outer band are utilized to form the gas and airbypasses around the rotor, or specifically around the heat transferplates 24 carried in the other compartments, and dampers are provided tocontrol the flow of by-passed gas or air through these by-pass chambers.Each of the chambers 30 is provided at one end, for example at the topor air inlet and .gas outlet ends thereof, with individual dampers 32mounted for rotation about the horizontal axes that extend radiallythrough the chambers centrally of the width thereof. The end portion ofthe shaft 33 for each damper projects outwardly through the rotor shelll2 into the space 34 between it and housing l8 and is provided with apinion 35 by which the damper may be turned from open to closed positionand vice versa. The shaft 33 also has a locking block 36 which maintainsthe damper in these extreme positions, as will be described later. Onthe inner wall of the housing plate Hi there are provided verticalguides 40 (Figures 4, '5 and 6) for a number of sliding supports 4| eachof which carries a toothed rack segment 42 mounted in radial locationfor movement vertically into and out of position for engagement with anydamper pinion 35 that registers therewith as the pinions traverse thecircle of rotation with the rotor. A plurality of these rack assembliesare provided on the air side of the preheater at the circumferentiallocation of the air passage 2-2. In the form chosen for illustrationthere are nine of these assemblies functioning for the eight chambersthat may be disposed at any one time within the circumferential ambit ofthe air openings 22 of the end plates 20, 2|. If desired the dampers mayalso be operated 'to create a gas by--pass and for this purpose thedrawings show eleven stations on the gas side; at these and at the ninestations on the air side, the pinions '35 of the dampers may bemomentarily engaged with the racks "42 to open or close dampers 32 foreight chambers on the air side-and ten on the gas side, there being onemore operating station in each instance than the maximum number ofchambers it is desired to expose at one time because both opening andclosing operations are involved.

To maintain the dampers '35 in either open or closed position a lockingrail 66 is mounted on the housing 18 and extends circumferentiallyaround the rotor L in aipos'i'tion alined with the lockingb'locks 36 onthe damper operating shafts 33 so as to-n'orma'lly engage these blocksas they move with the rotor 'andthus prevent'turning of shafts 33thereby holding the dampers in closed or 'open position. The lockingrails 48 include movable sections 4 8 provided at each damperoperatingstation'and mounted on the slide blocks 4] along with thetoothed gear segments 42 so that when one of the latter is moved downinto position (Figure all for operating the dampers the related railsection 4'8 is moved down out of locking position 'to free the passingdamper shaft 33 for rotation since the related locking block 36 can nolonger contact the movable section 48 as it passes the station'of thelatter because the section "48 has'been'retra'cted to provide room toturn the'blo'ck 36 and 'thus'it's shaft 33 and damper 32 also. Eachslide block 42 is provided with an operating rod 5i! connected at oneend to a pivoted operating lever "52 extendlng'throu'gh the rotorhousin'gfor "operation from the exterior'of 'the 'preheater so th'atthedamper actuating mechanisms may be "selectively operated in variousicombinations.

Assuming, for example, that less than maximum by-passing of air isdesired; this involves the movement to open position of a number of thedampers associated with the eight chambers that may be exposed at onetime to the air stream due to being included within the ambit of the airopening 22, but less than all of the eight at one time. in the diagramsof Figures 10a to 10) it is assumed that the air Joy-pass is toconstitute six chambers of the eight possible; hence, as the chambers 30enter the air passage all of the dampers 32 must be controlled so thatsix remain open atone time while the rotor ill traverses the airpassage.

When it is determined (as by observation or automatic signal) that theposition of the rotor I0 is such that all of the pinions 32 are locatedintermediate the stations of the racks t2 so as not to be engaged withor opposite the latter (Figure 10a), the rack segment 62B at the 2ndoperating station on the air side is moved to effective position(downwardly in Figures 4 to 6 and 10) while at the same time the relatedmovable locking rail section 48B follows this movement and becomesinoperative to engage the locking blocks 36 as they pass. .It will benoted in Figure 10a that having passed the 1st station the locking block36A for damper 32A rides upon the fixed locking rail segment 46A and thepinion 35A is held against rotation. Observe that all of the lockingblocks 35Q to 36X for all dampers shown in advance of 32A are inengagement with fixed segments of rail 46 and thus the related pinionsand dampers are held against rotation.

When the adjacent movable locking rail section- 28B was renderedinoperative it was retracted to a position in which clearance wasprovided (Figure 4a) for permitting rotation-of the square locking block35A along with the damper shaft 33 and dampertZ. In Figure 1% thepinion-38A may be seen to be engaged with the rack lia? and is beingturned thereby to open damper 32A. Note also that for all dampers inadvance of 32A which -is being turned by rack 4:25 the related racks 42Cto #21 are :in the up position where they do not engage the pinions 35and the latter and the related dampers are held against turning by therailsegmentslac to 481 engaging the blocks 36. Upon progressing-past the2nd-station the locking block 36A engages the locking rail section 460(Figure lilo) to retain the related damper 32A in open position.

In traveling past the-3rd,. 4-th,-5th,'6th and a'lth stations (the lastfour of which :are omitted to simplify Figure 10) where the racks 42 areineffective-the locking block "3 3A en-gages the movable-rail sections-48C, Minute. (Ei-gures lilcand 10d) in crossing the spaces betweenfixed rail sections '43 so that the damper 32 A remains held in openposition. When observation through :a Window in the housing It, or asuitable-signal, indicates that the pinion 5.43 for damper :32A isbetween the 'l'th and 8th stations Figure :iOcZ) the rack 42H at thelatter station is moved to effective position and the rail section 43Hout of locking .relation. At this time the pinions 35B to for fivedampers "following 35A for the damper 32A have been actuated in turnupon passing and engaging the-rack 42B .at the 12nd station.

Upon reaching the 8th station where (the-rack 42H has been lowered toeffective positiontthe pinion 35A is engaged (Figure .106) turning thedamper 32A rough a half revolution in the same direction as at the 2ndstation and the damper 32Anow closes. When the rotor turns to carrypinion 35A beyond the 8th station its locking block engages fixed railsegment 46H (Figure 10f) and is held in closed position. As the rotorcontinues to turn the damper 32A will remain closed as its chamber topasses the imperforate part 2'5 of the end plate that separates airpassage 22 from gas passage 23, which last it traverses in closedposition (provided no stations on the gas side are rendered operative)and it eventually returns to the air passage. The 1st station therein ispassed without incident but at the 2nd station the rack 4213 again opensthe damper 32A and dampers 3213 to 32H.

As the rotor turns, the pinions 35 associated with each of the dampers32 for the various chambers of the rotor becomes engaged in turn withthe operative 2nd gear rack c213 and riding along the rack is turnedbetween stations 2 and 3 to move the related damper from closed to openposition. As each pinion 35, carried along with the rotor Ill, movesbeyond the effective station the related locking block 36 again engagesthe locking rail 46 in section %C and the pinion cannot be turned tomove the damper. Inasmuch as partial by-passing is desired, all of theracks at other stations between the 2nd and 8th remain inoperative. Atthe 8th station the rack segment hEH (Figure 10d) is moved intooperative position just before the first damper to be opened reaches itso that as various pinions 35 pass by they will be engaged (Figure lile)and turned to rotate their dampers back to closed position. In themeantime because the intermediate operating stations and their apparatusare inoperative, the dampers for six of the eight of the chambersconfronting the air openings in the end plates are in open position asthe chambers traverse the air passage so that air is bypassed throughsix chambers at one time (Figure 9). In the example given, six dampersare opened in succession providing the cross-sectional area afforded bysix chambers for the flow of air around the rotor. As the seventh,eighth, ninth, tenth and other dampers open, the first, second, etc.,close. When the gas pass is reached the dampers stay closed, unlessstations there are put into operation, and on full rotation of the rotorthe first damper opens again as the cycle repeats.

It is possible to open the chamber dampers as they become alined withthe air passage and then close them upon leaving the latter thusproviding a full by-pass of eight chambers (Figure 8). Any lesser numbermay be operated generally as described above. With all racks d2inoperative all dampers are closed so there is no by-passing of air orof gas (Figure '7). Partial by-passing is brought about for example bymoving the rack 42A at the first station into operating relation and ifit is desired to have four or five chambers, counting from the leadingedge of the air aperture in open position, then the racks 42E, 12E atthe fifth or sixth stations are rendered effective to close the dampersas they pass. The intermediate racks have no effect upon the dampersbecause they are up out of position for engagement by the pinions andthe dampers remain open because of engagement of the locking blocks 36with the locking rail at as they pass through the intermediate stations.The same is true of the dampers as they pass stations beyond the fifthor sixth because these operating racks 42G, 42H, 421 are out of actionand thus the dampers, having been opened as they enter the air passageoperating position to and closed in passing the remain closed intraversing air passage. It is also possible to have some of the dampersadjacent either the leading or trailing edges of the air passage closed;that is to say, that dampers are opened when the chambers become alined,for example, with the central pore tion of the air passage. This is donefor exam ple by rendering the first two racks MA, 423,

inoperative while moving the rack 32C at the.

third station into position to open the dampers. When three chambers areto constitute the bypass, the third following station is renderedeffective by movement of its rack (e. g. t2?) to close the dampers asthe pinions engage the rack in passing by. Thus, any

number of chambers may be utilized to constitute the by-pass. Further,the location which the bypass assumes between the extremecircumferential margins of the air aperture is determined by theselective operation of racks at corresponding stations.

The operation of dampers to provide a maximum or partial by-pass for gasis exactly the same as for air and is effected by means of operatingmechanism in stations adjacent the gas apertures 23 of the end plates29, 2 l. When both air and gas by-pass arrangements are installed, thechamber dampers opening upon alinement with the air passage and, closingbefore or when leaving the latter, would remain closed until againalined with the air passage; provided the mechanisms on the gas side ofthe apparatus remain completely inoperative. However, if some gas alsois to be by-passed, the dampers having closed on exiting from the airpassage open again upon entering the gas passage, or at a desiredlocation therein, and subsequently close on exiting from the gas pass tobe again opened when in the operating cycle they return to the airpassage. It is deemed unnecessary to attempt to describe all possibleoperating combinations because the general manner of operation will beapparent from the foregoing examples.

It will be seen that the by-pass is built into the preheater itself. Thearrangement also provides great flexibility in allowing various volumesof air or gas to be by-passed due to the selective operation of thedampers for a number of rotor chambers which constitute a large or smallbypass or as desired.

What I claim is:

1. In apparatus having a cylindrical rotor divided by radial partitionsinto a plurality of wedge shaped compartments for carrying material tobe subjected to contact by gaseous fluids; circumferentially alignedtransverse partitions in each of said compartments forming similarlylocated chambers spaced in an annular band around the rotor; a housingsurrounding the rotor and provided with end plates formed with alignedcircumferentially spaced openings for the separated flow of said fluidsto and through the rotor; individual dampers adjustable between open andclosed positions for controlling fluid flow through said chambers;operating means connected to and carried by said dampers for moving themfrom open to closed position and vice versa; and stationary meansfixedly mounted on the housing in circumferentially spaced relationaround the rotor for actuating said operating means to selectively openand close said dampers.

2. In an air preheater having a cylindrical rotor divided by radialpartitions into a plurality of wedge-shaped compartments for carryingheat fourth or fifth station, the remainder of the accavcr transfermaterial to be subjected to contact by heating gases and air or-otherfluid to be heated; circumferentially aligned transverse "partitions ineach of said compartments segregating from said compartments a number ofchambers spaced around the rotor and disposed in corresponding locationsin said compartments; a housing surrounding the rotor and provided withend plates formed with aligned circumferentially spaced openings for theseparate flow of a heating gas and air to be heated to and through therotor: individual dampers adjacent the inner periphery of the rotorshell adjustable between open and closed positions for controlling fluidflow through said chambers; operating means connected to and carried bysaid dampers -for moving them from open to closed position and viceversa; and stationary means fixedly mounted on the housing in circ-uferen'tially spaced relation around the rotor for actuating saidoperating :means to selectively open and close said dampers.

3. Damper control apparatus as recited in claim 2 wherein each damper ismounted for rotation with a shaft extending axially of said chamber andprojecting'at one end into the space between the rotor and housing; apinion fixed to said end of said shaft; toothed racks engageab'le withsaid pinion mounted on the inner -1z eri-phery of the housing between-1said rotor and housing in predetermined spaced relationcircumferentially of the rotor in locations opposite the air and gasopenings; and individual means for moving said racks into position forengagement by said pinion, sai means being selectively operable to causesuccessive opening and closing movements of the related damper inpredetermined circumferential positions taken up by-eac'hcha-m- 8 herduring turning of the rotor through the arc" opposite one of saidopenings.

4. Damper operating apparatus as recited in claim 3 wherein lockingmeans are provided for positions.

'5.'Da1nper operating apparatus as recited in claim 4 wherein means areprovided for releasing the locking means for each damper prior toengagement of the related pinion with racks selectively operated to openand close said damper.

6. Damper operating apparatus as recited in claim 5 wherein said lockingmeans include; a locking block mounted adjacent the pinion on the shaftof each damper; an arcuate stationary locking rail positioned tonormally engage all said blocks during turning of the rotor so as toprevent operation of said dampers; and movable sections included ineachrail axially aligned with said pinion operating racks and movable toposi tions to interrupt the arcuate continuity of said rail so as tounlock each pinion for operation -by a rack that has been selectivelyadjusted to actuate the damper operating means.

7'. Damper operating means as recited in claim 6 wherein said movablerail-sections are moved to unlocking positions simultaneously with themovement 'of related racks to operative position.

References Cited the file of this patent UNITED STATES PATENTS

